This invention relates to a combinatorial weighing apparatus and, more particularly, to a semiautomatic combinatorial weighing apparatus wherein an operator manually supplies the combinatorial weighing apparatus with articles to be weighed.
An example of a conventional combinatorial weighing apparatus includes a plurality of weighing hoppers and a weighing machine provided for each weighing hopper, each weighing hopper and weighing machine forming a pair. Batches of articles introduced into each weighing hopper are weighed, a combinatorial computation is performed using a plurality of weight values obtained from the weighing machines, there is selected an optimum combination having a combined weight value which agrees with or is closest to a target weight, and solely those articles contained in the weighing hoppers having a total weight equal or closest to the optimum combination are discharged, whereby there is obtained a batch of articles having a weight which is equal or close to the target weight value.
To raise the speed of the weighing operation in a combinatorial weighing apparatus of this type, a pool hopper is provided above each weighing hopper and it is arranged so that a weighing hopper which has discharged its articles, owing to participation in the optimum combination, is immediately supplied with articles for the next weighing cycle by the overlying pool hopper. An emptied pool hopper is supplied with articles automatically or by a manual operation performed by an operator.
With the above-described arrangement, the number of pool hoppers provided is the same as that of the weighing machines and, hence, of the weighing hoppers. This increases the number of component parts or results in a more complicated arrangement and raises cost. In particular, in the case of a so-called semiautomatic combinatorial weighing apparatus adapted so that articles are introduced into the pool hoppers by a manual operation, it is difficult to introduce the articles, in a short period of time, into pool hoppers of a number equal to the number of plural weighing hoppers participating in an optimum combination. Moreover, since the number of pool hoppers is large, they are disposed over a wide area. Therefore, an operator cannot perform his task efficiently, or there is a need to increase the number of operators. Though a countermeasure might be to reduce the number of weighing machines themselves, this would inevitably diminish weighing precision.
Further, a semiautomatic combinatorial weighing apparatus is provided with an article supply table on which articles to be introduced into the pool hoppers are placed in advance. It is desirable that the supply table be disposed as close to the tops of the pool hoppers as possible and within easy reach of the operator. With such an arrangement, however, the construction is such that the pool hoppers and their underlying weighing hoppers are covered by the supply table. As a result, cleaning these hoppers, which is necessary from the viewpoint of sanitation, becomes a difficult affair. This is particularly true with regard to the cleaning of weighing hoppers situated below the pool hoppers. Furthermore, provided below the weighing hoppers is a collecting conveyor for collecting weighed articles discharged from plural weighing hoppers participating in the optimum combination. Cleaning the conveyor is also difficult because it underlies the weighing hoppers.
As mentioned above, the pool hoppers are disposed above the weighing hoppers to hasten the supply of articles, used in the next weighing cycle, to weighing hoppers which have discharged their articles. However, owing to this arrangement in which the pool hoppers are disposed so as to overlie the weighing hoppers, a problem arises in connection with a gate provided on each weighing hopper. Specifically, the hopper customarily has a discharge outlet provided on a lower side face thereof, with a gate being pivotally attached at its upper edge portion to the upper part of the discharge outlet. The discharge outlet is opened and closed as the lower part of the gate swings back and forth. With a construction of this type, the weight of the articles within the hopper acts upon the gate in such a manner that the gate is forced open. For this reason, a spring and a toggle-type link mechanism or the like are necessary in order to hold the gate closed. The result is a gate actuating mechanism of great complexity.
A solution to this problem would be to provide the hopper with a gate which opens and closes the discharge outlet by moving up and down along the opening of the discharge outlet, which is provided on the lower side face of the hopper body. The gate normally would be held in a closed position under its own weight but would be designed to be opened in an upward direction upon receiving an externally applied force. With such an arrangement, the weight of the articles within the hopper would act upon the gate in a direction at right angles to the opening direction, so that the gate would be held closed in reliable fashion without using a spring and link or toggle mechanism. In order to provide a wide discharge outlet the gate must be raised upwardly to a position where it would project from the upper side of the hopper body. If the hopper is a weighing hopper and a pool hopper is disposed above the weighing hopper as in the above-described arrangement, either the gate cannot be raised high enough or a great amount of space must be provided between the weighing hopper and the overlying pool hopper. The result is an inconvenience in either case.